Special Features of Book Classification.
The physical form of books demands certain distinctive additions to the special classifications before the schedules can be termed a book classification. They are:

- A Generalia Class: The main class of a classification which is reserved for books on many subjects such as Encyclopaedias.
- Form Classes: Those parts of a classification in which the books are arranged according to the form in which they are written, e.g. poetry, drama, fiction, essays, etc., the subjects of the books being ignored.
- Form Divisions: Adjuncts to a classification which enable books to be arranged (within their subject) according to the form in which they are written. They usually have a mnemonic notation which can be applied to any part of scheme.
The following further auxiliaries are necessary before these schedules can be used to arrange a collection of books on the shelves of a library:
- 4. A Notation: The symbols which stand for the divisions in a scheme of classification.
- 5. An Index: A detailed alphabetical list or table of topics, name of persons, place, etc., treated or mentioned on a book or series of books, pointing out their exact positions in the volume, usually by page number (sometimes with an additional symbol indicating a portion of a page) but often by section, or entry number.